It has been found that the free acid form of (−)-hydroxycitric acid is unstable, forming lactone (FIG. 1) which generally do not possess the desired bioactivity and also the liquid form of HCA tends to be unstable during storage. Therefore, food preparations that incorporate the free acid in liquid form will not provide the full benefit of the HCA in the final preparation.

A number of patents have been granted for the preparation of (−)-hydroxycitric acid salts. Singh, et al., Biol. Memoirs, 1995, 21, 27–33, describes the preparation of calcium salt of HCA. The drawback of this salt is not very soluble in water. Majeed, et al., U.S. Pat. No. 5,783,603 (1998), disclosed the preparation of potassium salt of HCA, but it is hygroscopic and has strong pungent taste. Ganga Raju, G. PCT Publication No. WO 99/03464 (28 Jan. 1999) described the preparation of calcium and potassium or sodium double salts of HCA and its use as dietary supplements and food products to reduce body weight. Balasubramanyam, et al., U.S. Pat. No. 6,160,172 (2000), disclosed the preparation of similar double salts of HCA.
Calcium gives bones their strength, while magnesium helps them maintain their elasticity to prevent injury. The more calcium in the diet, the more magnesium that is needed. Calcium given alone can induce a magnesium deficiency. The most serious complications from a deficiency of magnesium are heart conditions such as irregular heartbeat and rapid heartbeat (Bariscode, M. et al., American Journal of Nutrition, 1996, 19, 296). The magnesium recommended in USA by the Daily Reference Intake (DRI) is 420 mg for males and 330 mg for females. So it is good to have good calcium and magnesium in our daily diet or supplement. Shrivatstava, et al, U.S. Pat. No. 6,221,901 (2001) disclosed the magnesium (−) hydroxycitrate as dietary nutritional supplement.
Zinc is an essential mineral that is found in almost every cell. It is needed for wound healing, sense of taste and smell, DNA synthesis and it supports normal growth and development during pregnancy, childhood and adolescence. The DRI's of zinc for adult male is 11 mg and for adult female is 8 mg.
There exits a need for a stable and highly water soluble (−)-hydroxycitric acid salts that overcome the above drawbacks of insolubility, pungent taste and should have more number of desired minerals for health benefit.